Polyisocyanate-hydroxy aliphatic hydrocarbon substituted siloxane coating composition



POLYISOCYANATE-HYDROXY ALIPHATIC HY- DROCARBON SUBSTITUTED SILOXANE COAT- COMPOSITION u Leonard M. Shorr, Pittsburgh, ,Pa., assignor to Dow Corning Corporation, Midland, Mich., a corporation of Michigan No Drawing. Application March 7, 1955 Serial No. 492,132

- Claims. (Cl.260-.-46.5)

This invention relates to amethod of applying organosilicon compounds to organic fibrous materials and to some of the compositions soapplied.

It has long been known that organosilicon compounds produce water repellent surfaces when applied to practically any material. They have met with oustanding success with respect to textiles particularly wool and synthetic textiles. 'Heretofore employed organosilicon compositions also render cotton and other cellulosic fibers waterrepellent. However, after 1 or 2 launderings the water repellent film is completely removed. This phenomenom is presumably due to the much more drastic treatment to which cotton is subjected during laundering than are other types of fabric. As a consequence of this defect heretofore employed organosilicon water repellents have not met with much success in the treatment of cotton.

Another defect which has been inherent in heretofore employed silicone coating compositions has been the deterioration of the coating when subjected to hydrocarbon'solvents. This defect is overcome with certain of the compositions employed in the method of this invention. 7

It is the object of this invention to provide a method ofrendering organic fibrous materials water repellent. Another object is to provide a durable water repellent treatment for cellulosic fabrics. Another object is to provide improved coating compositions which are resistant to hydrocarbon solvents. Other objects and advantages will become scription.

In accordance with this invention a composition of from 1 to 50 mol percent I and from 50 to 99 mol percent R ",.SiO

in which R is a divalent saturated aliphatic hydrocarbon radical or a divalent saturated cycloaliphatic hydro- I apparent from the following del v hydrogen so as The compositions above described may be applied to the organic fibrous material in any desired manner, for example, the material may be clipped in the coating composition or the coating composition may be brushed,

sprayed or flooded on the fibrous materiaL. The coat-, ing composition' may be in the form of a solution but if solvents are employed, they should be free 'of j'activ'e, not to interfere with the isocyanate cure."

The term organic fibrous material includes suchjina terials-as cotton, rayon, ramie, nylon, silk, polyester fiber'sfwool, linen, paper, wood and leather. Preferably the amount of isocyanate employed is in excessofthat required to react with all of the HOR groups in the siloxane. It is believed that the excess isocyanate groups react with any active groups on'the surface of the fibrous material. Thus, the isocyanate not only cures the sill} cone but also actually bonds it to the. surface of the fibers by chemical bonds. This may account for the, greater durability of the instant treatment on cotton than has heretofore been obtained.

Thesiloxanes which are useful in the method ofthis invention are copolymers of the above-defined hydrox ylated siloxanes and conventional siloxanes. The relative proportions of the hydroxylated siloxane and the conventional siloxane may vary depending upon the properties desired in the finished coatings. In general, greater heat stability is obtained when small amounts of the hydroxylated siloxane is employed. On the other hand,

faster curing and greater resistance to hydrocarbon solvents are obtained with higher amounts of the hydroxylated siloxane. 1 V I For the purpose of this invention R can be any divalent saturated aliphatic hydrocarbon radical of at least three carbon atoms such as propylene, butylene and octadecylene and any saturated cycloaliphatic divalent hydrocarbon radical of at least four carbon atoms such CL CH:- clni I and monovalent hydrocarbon radical or hydrogen, and m carbonatom away from the silicon means that the hydroxylis no closer than the carbon from the silicon atom.

R' is any saturated monovalent hydrocarbon radical free ot aliphatic unsaturation such as alkyl radicals such as methyl, propyl, butyl and octadecyl; cycloaliphatic radi-' cals such as cyclopentyl and cyclohexyl; aromatic hydrocarbon radicals such as phenyl, tolyl, naphthyl and xenyl; and alkaryl radicals such as benzyl and any halogenated monovalent hydrocarbon radical which is free of aliphatic unsaturation such as chlorophenyl, tetrafluoroethyl, a,a,a-trifluorotolyl and chlorotrifiuorocyclobutyl. The symbol S has been used above to indicate that the ring systems within which it occurs are saturated ,cycloaliphatic radicals. In the process of this invention n may have a value from 0 to 2 so that the. functional siloxane units can be of the formulae HORSiO HORR'SiO and HORR' SiO or any combination of hes The siloxanes employed herein can be prepared in accordance with the method described in the copending application of John L. Speier, Serial No. 463,061, filed October 18, .1954.

The siloxanes employed in this invention also contain siloxane units of the formula amnion...

in which. R" is any monovalenthydrocarbon radical 10 such as 'alkyl radicals such as methyl, ethyl andocta decyl; 'alkenyl radicals such as. vinyl, allyl and hexenyl;

cycloaliphatic radicals such as cyclohexyl, cyclopentyl andjcyclohexenyl; aryl hydrocarbon radicals such ;as

phenyl, xenyl, tolyl andinaphthyl and alkarylhydrocarbon' i idicals, such. as. benzyl. R". can also be any/haloenated monovalent hydrocarbon radicalsuch as. tetraflUOIQeihYl, bromophenyl, hexabromoxenyl, mega-trifluorotolyl, trifluor'ovinyl, and tetra'fluorocyclobutyl. In these siloxanes .m has an average value from l t-- 3 nclusive. Thus the siloxane can contain any combination of units of the. formulae R"SiO RQSiO and Rj'fgSiQ together withlimited amounts of SiOg' units.

In the above formula when m is 2 and R" is methyl or hydrogen, the units can be defined as having the formula. (CH H SiO wherex has a value ofgfrom 0 to. 1 inclusive. i g

The compositions employed in this invention can be eluted, by employing any polyisocyanate, i.e.-, any iso cyanatecontaining at least 2 isocyanate groups per molecule. Specific. examples of isocyanates which are operative, in this invention are aromatic isocyanates such as toluene 2,4 diisocyanate', 2enitrodiphenyl-4,4-'diisocyanate; lenitrodiphenylrnethane4,4-diisocyanate; diphenyl methanesulphone-4,4-diisocyanate; diphenylsulphone 4, 4'-diisocyanate; naphthylene-1,4-diisocyanate; naphthylene-l,5-dii's,ocyanate; naphthylene-Z,T-diisocyanate;V fiuorene diisocyanate and, chryseneediisocyanate'; and ali-' phfific. isocyanates, such as hexamethylene. diisocyanate, butylene' diisocyanate and octadecylene ,diisocyanate; and

, 1.40 cycl'oalipha'tic diisocyanates such as cyclohexylene diisos}- treated that the pickup of siloxane on the fabric be from .2 to 5% by weight. Fabrics which are treated in this manner show no decrease in water repellency after several conventional launderings.

It has been found that certain compositions within the scope of this invention are not only useful for rendering organic fibrous materials water repellent but also give coatings when cured which are particularly re-f sistant to hydrocarbon solvents. These compositions are" therefore quite useful for protective coatings on other types of. materials such as metals, gIass ceramic'and' organic plastic surfaces.

The. compositions which have this particular utility are-those having from 1 to 50 mol percent above defined. I It is to be noted that these com positions -oalin' be curet y; ny o nt ona man ...v is... he curingget these compositions in' order to get the solvent resistant coating is not restricted to-the use of isocyanates. They can be cured by heat alone or by the use of siloxane bond rearranging catalysts or by the use of other organic polyfunctional materials which will react with hydroxyl groups such as dibasic acids. It is advantageous, however, to .employ isocyanatesas the curing agent sincethe.

cure proceeds morerapidly with these materials. 'In

any event it is preferable to heat the resin attemperatures of 150 to 250 C. in order to insure proper curing.

These solvent resistant-protective; coatings maybe applied to the base "member in any desired-manner such as by dipping, spraying, brushing or flooding. "The coatings mayalso contain any desired pigment or fillers or other materials which are conventionally employed in connection with protective coatings.

The following examples areillustrative only and should not be construed as limiting the invention which is properly delineated in the-appended claims. The symbols Me, Ac, Vi, andEt, are-used throughout thespecification and examples to represent :methyl', acyl, vinyl andethyl' radicals respectively. a

, Y Exam le 1-' I vA mixture of 195.6 gof methyl hydrogen .dichlorosilane. and 64.6 g. of gamma-acetoxypropyhnetlryldichlorosilane was. added with?stirring'.;to a:mixture :of 35.0 g. of toluene.-.and .3Z6?.g.;r f:.water. After :cohydrohzsis' was complete the copolymer solution: was: washed until neutral andthetoluene solution was iconcentrated to '7 0% by-weightasiloxane.

95 g; of this "10% solutionv wasdiluteddwith fi 'g; of

toluene and 150 :g. :ofmethanol. A: catalytic quantity of benzenesulphonic acid was added :and 'thematerial allowed to stand at room temperature for 7 days; The solution. was-.-.thenzwashed with-water and dried by azeotropic-distillationruntilthe. weight of:the:solution reached 95:,g. The resultingmaterialawash solution ofa'cop'oly mer; of [5' mol :percentfv gamma-hydroxypropylmethyl siloxane and 85 mol percentmethyl :hydrogenisiloxane'.

3 g. of the above solution and 1 g. of m-tolueneczdiiso cyan'ate were; dissolved in '153: .g. of toluene; A piece of cotton: cloth wast dipped rinto; thisi solutionithen; re-

moved therefrom and airedried; The cloth. was water repellent and waspfound tohave a gpickup of 1.2% by weight-of .the-combi-nedz-silicone and diisocyanate. The cloth was laundered:= with; soapcandiwater' and, after laundering-was foundzro b.e .-eas water: rrepellent-as beform laundering. :-.:Examplei2 The siloxane employed in this eitamplewas a copol ymer of 55 mol percent phenylmethylsiloxane, 15 mol percent monophenylsiloxane'i 15 mol percent monomethylsiloxane and 15 mol percent 3.5 g'; of thislresiniand of metolue'ne ,diis'ocyanate were dissolved in 219g of tol'u'eneltolgi'vie aliii .solu

tion of combinedsiloxane rand isocyanate. Amstrip of.

cotton gauze wasdipped into. solution andwa'sremovedtherefroml and allowedlto dry'lat25. CL The inWeIight or the.lcloth"was4%l The .cIoth wasfwaten. repellent-as shown by the fact. thatitLwonldlsupmrt.

a drop of water.21hoursleven..after beingcrumpled: It. i $0 trr 9,9j mol percent Me SiO'. and 0 to 35 mol) percent- MeSiOm in which compositions R, R" and nv .are as 1 Water,,.rinsed,and, dried. at I380 C210: -5 v gauze was still aswater'repell'entas before.

found torender leather water repellent.

r I Example 3 QTh'e siloxane resin employed in this example was prepa'r'ed'as follows: A mixture of 64.5 g. of dimethyldichloros ilane, 523g. of methyltrichlorosilane and 42.2 g. of

was added' with stirring to a mixture of 218 g. of

toluene and 100 ml. of water. As hydrolysis was complete the organic layer was washed until neutral, and azeotropically dried. One pellet of potassium hydroxide dissolved in 1 m1. of ethanol was added and the Solution was refluxed for 6 hours at a concentration of 25% resin solids toremove all of the water. A slight excess of trimethylchlorosilane was added to neutralize the alkali and the solution was then concentrated to 70% solids in toluene.

This resin solution was then dissolved in a mixture of 10 g. of KOH, 50 g. ofethanol and 100 ml. of toluene. The solution was refluxed for 3 hours to saponify the acetoxy group. The resulting product was washed with water and neutralized with HCl. The resulting 'product was 'azeotropically dried and concentrated to 70% solution in toluene. The resulting siloxane resin had the following composition: '50 mol percent dimethylsiloxane, 35 mol percent monomethylsiloxane and molpercent nocnr-l 8.3 g. of this 70% toluene solution was mixed with .9 g. of m-toluene diisocyanate. A sheet of iron was coated with the solution and cured at 250 C. for minutes giving a hard, tough, glossy, very flexible film. The resulting film was not attacked by toluene after 2% hours of complete immersion.

2.3 g. of the above siloxane resin and l g. of m-toluene diisocyanate were dissolved in 163 g. of toluene. Cotton cloth was dipped into this solution, air dried for A hour and was found to be water repellent. The cloth remained as water repellent after vigorous washing with soap and water and after immersion in carbon tetrachloride.

Example 4 A siloxane resin having the composition 85 mol percent dimethylsiloxane and 15 mol percent HO(CH SiO (thus having an average of 1.85 silicon-bonded organic groups per silicon atom) was prepared in accordance with the general procedure of Example 3. 2.1 g. of this resin and 1 g. of m-toluene diisocyanate were dissolved in 150 g. of toluene. A piece of cotton cloth was dipped into the solution and air dried for 45 minutes. The pickup on the cloth was 2.1%. It retained its water repellency after washing with soap and hot water and after cleaning with carbon tetrachloride.

Example 5 Water repellent fabrics are obtained when rayon, paper, wood and nylon are treated in accordance with the proeedure of Example 1.

. 6. Example 6 Water repellent cotton is obtained when .a copolymerof 10 mol percent ViMeSiO, 20mol percent CIC I-QSiO 25 .mol percent p i g Et Me FlC=CFSl0 20 mol percent H0(CH );SiO and 5 mol percent 10 mol percent Me nowmnwwmosro; is applied in the manner of Example 1.

Example 7 Me HO(CH;);SIO

This material was neutralized by washing the organic' layer with distilled water. 50 g. of diisopropylketone were added to the solution and the neutral'resin was dried by azeotropic distillation, filtered'and concentrated to 70% solids. Additional isopropylketone was added to keep the material in solution.

1.4 g. of the above resin and 1.1 g. of m-toluene diisocyanates were dissolved in 119 g. of the toluene. Cotton cloth was immersed in this solution for about 1 minute and air dried 20 minutes at room temperature. The cloth was then heated at C. for 20 minutes. The resulting cloth was waterrepellent and remained so after washing with Lava soap and water. The cloth was also water repellent after dry-cleaning with carbon tetrachloride.

That which is claimed is:

1. A method of rendering an organic fibrous material water re'pellentwhich comprises applying to the fibrous material a solution in an inert organic solvent of a composition comprising (1) a copolymer consisting essentially of from 1 to 50 mol percent siloxane units of the formula in which R is of the group consisting of divalent saturated aliphatic hydrocarbon radicals and divalent saturated cycloaliphatic hydrocarbon radicals in all of which the hydroxyl is attached to a carbon atom which is no closer than the third carbon atom from the silicon, R is of the group consisting of monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, all of which are free of aliphatic unsaturation and n has an average value from 0 to 1 inclusive and from 50 to 99 mol percent siloxane units of the formula R,Si0 in which R" is of the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and hydrogen, there being not more than one hydrogen atom attached to any one silicon atom, and said copolymer having an average of at least 1.85 silicon-bonded organic groups plus silicon-bonded hydrogen atoms per silicon atom, and (2) an organopolyisocyan'ate in which the isocyanate substituents are the only substituents present which are reactive in the system, and thereafter allowing the composition to dry.

access? I 2. An organic fibrous material treated by the method of claim 1. n

'3. Amethod dfrendering -a v cellulos'ic fibrous material waterrepellent which comprises applying to-the-fibrous material a composition comprising (1) a copolymer consisting essentially of from" 1 to 50 mol percent siloxane units of the formula R. HORSiO T in which R is. ofethe group consisting of divalent saturated aliphatic hydrocarbon radical s 'and divalent saturated cycloaliphatic hydrocarbon radicals in all of whichthe hydroxyl is attached to'a carbon-atom which is no closer than the third carbon atomfrom the silicon,- R? is of.

the group consisting df rnon'o'valent hydrocarbon radicals and halogenated monovalent, hydrocarbon radicals all of which are free of aliphatic unsaturation and n has an average value from 0 to 1 inclusive and from 50m 99 mol percent siloxane units of the formula R SiO in which R" is of the group consisting of'monovalentorganopolysiloxane consisting offrom 1. to 50 mol percent siloxane units of the formula in which-R is oi the group consisting of divalent saturated aliphatic hydrocarbon radicals and divalent saturated cycloaliphatic hydrocarbon radicals in allot; which the hydroxyl is attached to a carbon atom which. is-no.

closer than the 'third carbon atom awayfrom thesilicon, R is'of'the group-consisting of'monova'lent hydrocarbon radicals and halogenated monovalent .hydrocarbonradicalsallof-which are free -of aliphaticunsaturationand n hash value from -0 to 1 inclusive, and from 50 to 99 mol; percent: dimcthylsiloxane units said copolymeric organopolysiloxane having an average of at least 1.85 silicon-bonded organic groups per silicon atom.

6. A composition of matter-comprising (1) a copoly- 0, J r v than .the third carbon atom away from thesillcon, R

'50 to 99 mol percent dirnetliylsiloxane units, said comeric i organopolysilox ane consisting. essentially of irom 1 tofitlmol percent siloxane units oi. the formula v I My HORSiO in which R isof the groupiconsisting of'divale'ntsamrated aliphatic hydrocarbon radicals and divalent saturated cycloaliphatic hydrocarbon-radicals in all of which the hydroxyl is attached to. a carbonatomawhich is, no closer is of the vgroup consisting of monovalent; hydrocarbon radcials and halogenated monovalenthydrocarbon radicals all of which are free of aliphatic unsaturation and n has an average value from 0 to 1 inclusive, and from polymeric organopolysiloxane having an average of at least 1.85 siliconbonded organic groups per silicon atom, and (2) an organopolyisocyanate in which the isocyanate su-bstituents are the only substituents. present which are reactive in the system.

7. A method-inaccordance with-claim -3 in. which R is a n-propylene radical, R is amethyl radical, and R" Si0 represents a methylhydrogensiloxane unit;

8. :A: method of rendering a cellulosic fibrous materialwater repellent which comprises applying thereto a S0111-- ti'on; in an inert organic solventaof- (al-)- a copolymer-oi from I-to .50 mol percentsiloxanerunits ofi'theiormula HOCH CH CH (CH )Si0 and from 50 to 99 mol percent siloxane -units of theformula (CH hSiO, and (-2)= tolucne; diisocyanate; and thereafter drying said cellulosic material.

9.--A- composition of matter consisting essentially of a solutioninan inertorganic solvent-o:( 1) a'copolymerof-froml'to 50 mol-percent siloxane units of theformula HOCH CH CH (CH )SiO and- 50, to 99- mol percent siloxane units of theaformula (CH ,H Si O- where x' has? an average value ofsfrom' 0-to 1. inclusive and-(2") toluene diisocyanate.

10. A composition of matter consisting essentially of a solution in an inert organic solvent of (1) a copolymer of from 1 to 50 mol percent siloxane units of the formula HOCH CH CH (CH )SiO and 50 to 99 mol percent siloxane units of the formula (CH )HSiO, and (2) tolucne diisocyanate.

' References Cited in the. file: of this patent nsurer) STATES PATENTS 2,550,205 i' OTHER. REFERENCES peierr J.A-.c:s 101. 74; No. 4, Feb; 2'0; l 9'52,-pa'ge s 1003 -1010.: co inSSeientific Library)" UNITED STATES PATENT OFFICE CERTEFICATE or CORRECTION Patent 'Noa 2,92%587 February 9 1960 Leonard M9 Shorr ears in the printed specification 1 \It is hereby certified that error app rection and that the said Letters of the above numbered patent requiring cor Patent should read as corrected below.

fColumn 6 line 66 for "R 510" read R Si0 column 'l line 5 after "material" insert a solution in an inert organic solvent of; line 21 for "R SiO read R SiO Signed and sealed this 2nd day of August 1960,

SEAL) Attest:

KARL H, AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents 

1. A METHOD OF RENDERING AN ORGANIC FIBROUS MATERIAL WATER REPELLENT WHICH COMPRISES APPLYING TO THE FIBROUS MATERIAL A SOLUTION IN AN INERT ORGANIC SOLVENT OF A COMPOSITION COMPRISING (1) A COPOLYMER CONSISTING ESSENTIALLY OF FROM 1 TO 50 MOL PERCENT SILOXANE UNITS OF THE FORMULA 